Weibull analysis of cutting tools and dies

Arabic Abstract

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English Abstract

A large volume of data relating to cutting tool and die life, under different set of cutting and material conditions is retrieved from the literature and industry and the Weibull model is established as the most suitable model. The parameters of Weibull distribution for each of this data set are estimated by regression analysis and tabulated to serve as a data bank for further research work in this area. A mechanistic model is proposed combining the fracture mechanics and the fatigue analysis concepts in order to predict the life of extrusion dies using Monte Carlo Simulation. Comparison of the simulated results is made with the real life data collected from a local extrusion plant and the suitability of the model for the die life prediction is established. A statistical-mechanical model is also proposed to precisely predict the wire drawing die life distribution, considering abrasive/adhesive wear as the dominating mode of failure. Each of the input variables are assigned a predetermined statistical distribution and the effect of the randomness of these variables on the distribution of the wire drawing die life is observed. This simulated results are found to be in good agreement with the industrial data collected from a local wire drawing company. Keeping in view the higher costs associated with the failure replacement of tool/die when compared to the scheduled replacement, an optimal replacement interval is estimated for the Weibull distributed tool/die life data, on the basis of a scheduled replacement policy. A software package called "Mathematica", is utilised to solve the integrations involving nth convolutions is renewal functions.